Low Water Pressure in Your House? Causes and Fixes

Few things are more frustrating than a shower that trickles or a faucet that barely fills a glass. Low water pressure has a lot of possible causes — but the good news is that many are simple to track down. Start by answering one question: is it one fixture, or the whole house?

One fixture or the whole house?

If only one faucet or shower is weak, the problem is almost always local to that fixture. If pressure is low everywhere, the cause is further upstream — your main valve, a pressure regulator, your pipes, or a leak. This one distinction points you straight at the likely culprit.

Common causes at a single fixture

• A clogged aerator. The little screen on the tip of a faucet catches mineral scale — very common with our hard water — and chokes the flow. This is the number-one cause and an easy fix.
• A clogged showerhead. Same idea: scale builds up in the nozzles and weakens the spray.
• A worn cartridge. Inside the faucet, a failing cartridge can restrict flow.
• A partly closed shutoff. The valve under the sink or behind the toilet may not be fully open.

Common whole-house causes

• A failing pressure regulator. Many homes have a pressure-reducing valve near the main line; when it fails, pressure can drop (or spike).
• A partly closed main valve. If your main shutoff isn't fully open, the whole house suffers.
• Scaled or corroded pipes. In older homes, decades of mineral buildup narrow the pipes and cut flow throughout the house.
• A hidden leak. Water escaping from a hidden or slab leak diverts pressure away from your fixtures.

Quick things to check yourself

1. 1Unscrew the aerator or showerhead and soak it in vinegar to dissolve the scale, then rinse and reattach.
2. 2Make sure both shutoff valves at the affected fixture are fully open.
3. 3Confirm your home's main shutoff valve is all the way open.
4. 4If you have a pressure gauge, thread it onto an outdoor spigot — normal home pressure is roughly 45–70 psi.

When to call a plumber

If cleaning the aerator doesn't help and the problem is house-wide, it's worth having a pro diagnose the regulator, check for leaks, and assess your pipes. We handle low-pressure diagnosis, faucet and fixture repair, and leak detection across the West Valley, from Peoria to Goodyear. Because so much of the problem here traces back to minerals, our guide to Arizona hard water is worth a read too.